Many electronic devices and electrical enclosures contain electrical circuitry that emits electromagnetic signals. These signals often interfere with each other. Such circuitry is also susceptible to interference by electromagnetic signals generated by external circuitry and sources of electromagnetic disturbances. This interference is especially prominent in environments or equipment in which high frequencies (i.e., radio frequencies, for example) are present.
In order to minimize the effects of such interference on the performance of electrical devices, electromagnetic control (EMC) contact devices have emerged. These devices act to inhibit the transmission of such signals so that they do not interfere with adjacent or external circuitry. These devices also act to isolate signal-generating components within the device from the effects of external circuitry and sources of electromagnetic disturbances.
Such electromagnetic signals also cause electrical currents to be induced into conductive components within the device or enclosure. If the components are not connected in an electrically conductive manner, these electrical charges cannot be discharged. As the logic used in electrical devices becomes faster and faster, they become more and more susceptible to electrical charges. Over time, these charges build up and can cause malfunctions within and/or damage to the device. Reliable electromagnetic contact, therefore, is essential to the overall performance of the electrical device.
As a result, EMC contact devices are typically in the form of a compression-type gasket or like device which seals any gaps or clearances between the various components. In many electrical devices, however, it is desirable to have electrical components which are removable so that they may be readily repaired and/or replaced when needed. Conventional sealing-type EMC devices, therefore, are not practical.
As a result, EMC contact devices for enclosures having removable components have been developed. One approach to such EMC contact design is shown in FIG. 1. This approach involves using a conventional leaf spring 1 against two surfaces 3 and 5. When a force F1 is applied to surface 3, spring 1 compresses. The spring is also subjected to sliding forces F2 as is shown in FIG. 2A. Due to the design constraints of such springs, however, they have little axial strength and often cannot withstand the impact of such sliding forces. The shape of spring 1 may, therefore, be deformed or even destroyed upon application of such sliding forces, as is shown in FIG. 2B. When the shape of spring 1 is lost, reliable electromagnetic contact cannot be guaranteed. As a result, the overall performance of the device may be seriously degraded.
One way to further ensure reliable electromagnetic contact is by designing an EMC contact device having high contact density. High contact density, however, often comes at the price of a design which requires a significant amount of space. With the ongoing demand for miniaturized devices, such space constraints are not acceptable.
Accordingly, there is a need for a small-sized sliding EMC contact device that is immune to damage, that provides high contact force and high contact density, and that is easy and inexpensive to assemble and manufacture.